The Supreme Court asks whether the government can put a GPS device on your car without a warrant.

Antoine Jones was convicted in 2008 and sentenced to life in prison for possessing and conspiring to distribute more than 50 kilograms of cocaine. Key evidence in the case against him was obtained in 2005, when District of Columbia police got a warrant to secretly install a GPS device in order to monitor the Jeep Cherokee driven by Jones and his wife. The warrant expired after 10 days, but the police nevertheless used the GPS to monitor everywhere he drove, every 10 seconds, for 28 days. He led them to his “stash house” in a Maryland suburb, where they found powder and crack cocaine, plus $850,000 in cash. Jones tried to have his conviction set aside, arguing that warrantless GPS surveillance violated his Fourth Amendment right to be free of unreasonable government searches and seizures. The government replied that GPS tracking is no different from police observing activity in public spaces and roadways, which is not protected under the Constitution.

A panel of the D.C. Circuit Court of Appeals ruled last August in favor of Jones, finding that the government may not conduct protracted, around-the-clock GPS surveillance without a warrant. Judge Douglas Ginsburg, writing for the three-judge panel wrote that "the police used the GPS device not to track Jones' movements from one place to another, but rather to track Jones' movements 24 hours a day for 28 days as he moved among scores of places, thereby discovering the totality and pattern of his movements from place to place." Other federal appellate courts have agreed with the government that one has no expectation of privacy in activity open to public view on city streets.

Now, I know what you’re thinking: Given all the recent discussion of the extracurricular activities of Supreme Court justices, and their failure to disclose participation in various secret and/or partisan events, isn’t a GPS affixed to judicial vehicles kind of a great idea? Doesn’t America have a right to know where the justices go when they go places?

Chief Justice John Roberts (Metro station, kids’ school, Metro station, kid’s school) is way ahead of you, my friend. One of his first questions to Deputy Solicitor General Michael Dreeben this morning is just that: Would it constitute a “search,” he asks, “if you put a GPS device on all of our cars, monitored our movements for a month?”

Dreeben swallows and then asks carefully: “The justices of this court?” Then he starts to say that the justices driving on public roadways have no greater expectation of privacy than anyone else—but the chief justice stops him. “So you could tomorrow decide that you put a GPS device on every one of our cars, follow us for a month—no problem under the Constitution?” Well, no.

Justice Samuel Alito (ballgame, American Spectator dinner, ballgame) is a prodigious worrier about new technology and privacy. He puts it this way: “Most of the privacy people enjoyed was not the result of legal protections or constitutional protections, but the difficulty of traveling around and gathering up information. But with computers, it's now so simple to amass an enormous amount of information about people that consists of things that could have been observed on the streets.”

Then it’s time for Justice Ruth Bader Ginsburg (opera, opera, Aspen Institute, opera, elephant) to express her reservations. “The government's position would mean that any of us could be monitored whenever we leave our—our homes,” she says. “Is the end point of your argument, that an electronic device, as long as it's not used inside the house, is OK?”

Dreeben clarifies that the issue here is “monitoring somebody's movements in public. We are not talking about monitoring their conversations, their telephone calls, the interior of their cars, their private letters or packages.” Which sends Justice Stephen Breyer (Renaissance Festival, Omega Quadrant) into something of a Stanley Kubrick tizzy, asking about 1984 and “futuristic scenarios.”

Dreeben says there is no distinction to be drawn between a 1983 case in which the Supreme Court found no Fourth Amendment violation when cops affixed a “beeper” to a chemical container in the suspect’s truck. But that case involved a single car trip. In Dreeben’s view, “Under a principle of law that says one trip is OK but 30 trips is not, there is absolutely no guidance for law enforcement.”

Roberts suggests that a GPS is worrisome because it gives the government a massive of amount of information. Dreeben replies: “So does a pen register, so does a garbage pull. So does looking at everybody's credit card statement for a month.” But the court doesn’t deem those searches. Justice Anthony Kennedy (Salzburg, Berlin, Czechoslovakia, Russia, China, England, Greece, Wales) wonders whether the government can affix a GPS device to your overcoat. Justice Sonia Sotomayor (baseball game, Bronx, Manhattan) tells Dreeben that under his theory of the case, “You could monitor and track every person through their cellphone, because today the smartphones emit signals that police can pick up and use to follow someone anywhere they go. … They have no reasonable expectation that their possessions will not be used by you … to track them, to invade their sense of integrity in their choices about who they want to see or use their things!”

Justice Antonin Scalia (shooting range, Koch brothers meeting, opera, elephant) has a better solution: “Don't we have any legislatures out there that could stop this stuff?”

Stephen Leckar has 30 minutes to represent Jones, and he tries to advance a second argument in this case: The very act of installing the GPS device on a private vehicle constitutes a trespass. Earlier Kennedy—using his preferred early ‘80s terminology—had said he had “serious reservations about the way this beeper was installed.” But Alito wonders if a GPS affixed to your state-owned license plate represents a trespass. Scalia starts whooping. “I didn't own my license plate? I didn't know that. How do you know that? I paid for my license plate.” Scalia presses Leckar on what precisely has been seized here. When Leckar says his client’s data is seized, Scalia retorts, “Do you have any case involving seizure of data floating in the air as opposed to papers?”

Leckar says the government should not have the right “to take a device that enables them to engage in pervasive, limitless, cost-free surveillance.” But Kennedy stops him to ask how that’s any different from putting “30 deputies on this route and watch[ing] this person.” This leads Ginsburg to wonder how GPS tracking is any different than a surveillance camera. And Justice Elena Kagan (shooting range, opera, jury duty, shooting range) suggests that, “if somebody goes to London, almost every place that person goes there is a camera taking pictures.”

Leckar agrees: “It's pretty scary. I wouldn't want to live in London under those circumstances.” And Scalia sniffs: “Well, it must be unconstitutional if it's scary. I mean, what is it, the scary provision of what article?”

Breyer adds: “In fact, those cameras in London actually enabled them … to track the bomber who was going to blow up the airport in Glasgow and to stop him before he did.”

Leckar (recalculating) goes back to his physical trespass argument, which sends Breyer into something of a fit (for him, this means yelling, “Oh, my goodness!”). Then Sotomayor adds: “There are now satellites that look down and can hone in on your home on a block and in a neighborhood. I don't see that far in the future when those cameras are going to be able to show you the entire world and let you track somebody on the camera from place to place.”

Leckar tells Scalia that a GPS device without a warrant is like having “an uninvited stranger” in your car. Scalia asks again why this isn’t “precisely the kind of a problem that you should rely upon legislatures to take care of?” But Leckar is often unable to articulate a workable standard that could help the court resolve the differences between a one-day tail and one that lasts 30 days.

Dreeben begins his rebuttal this way: “Advancing technology cuts in two directions. … Today perhaps GPS can be portrayed as a 1984-type invasion, but as people use GPS in their lives and for other purposes, our expectations of privacy surrounding our location may also change.”

That’s enough for Kagan. “That seems too much to me,” she says. “I mean, if you think about this, and you think about a little robotic device following you around 24 hours a day any place you go that's not your home, reporting in all your movements to the police, to investigative authorities, the notion that we don't have an expectation of privacy in that, the notion that we don't think that our privacy interests would be violated by this robotic device, I'm not sure how one can say that!”

Kennedy wonders whether a neighbor could attach a GPS device to your car and monitor where you go without violating your privacy. Dreeben says maybe.

It’s long been a truism of Fourth Amendment law that the “reasonable expectation of privacy” test is circular. Each time the state chips away at your privacy, you expect a little less. So when Dreeben talks of those cute little beeper cases from the 1980s, and prophesies a future age in which we come to think of GPS devices as adorable little talking friends, he is really sketching out the contours of that ever-contracting circle. Just as the old glass phone booth and the “spike mike” cases seem archaic when it comes to data mining and pen traces, so someday the state knowing everywhere you drive will seem like a big nothing compared with what’s coming next. The justices seem well aware of that fact today, and completely on top of the technology coming down the road, metaphorical and actual—even if they’re unsure where to draw the constitutional lines.